This invention is an improvement over the inventions of several earlier applications, to-wit:
Ser. No. 08/130,290, filed Oct. 4, 1993 now U.S. Pat. No. 5,338,185, granted Aug. 16, 1994 in the names of Richard W. Henderson and George R. Lightsey;
Ser. No. 08/247,925, filed May 23, 1994 now U.S. Pat. No. 5,456,595, granted Oct. 10, 1995 in the name of Richard W. Henderson;
Ser. No. 08/297,048, filed Sept. 30, 1994 now U.S. Pat. No. 5,409,370, granted Apr. 25, 1995 in the name of Richard W. Henderson;
Ser. No. 08/365,804, filed Dec. 29, 1994 now U.S. Pat. No. 5,549,470, granted Aug. 27, 1996 in the name of Richard W. Henderson;
Ser. No. 08/514,583, filed Aug. 14, 1995 now U.S. Pat. No. 5,662,468, granted Sep. 2, 1997 in the name of Richard W. Henderson.
Ser. No. 08/559,922, filed Nov. 17, 1995 now U.S. Pat. No. 5,551,865, granted Sep. 3, 1996 in the names of Richard W. Henderson and Samuel R. Henderson;
Ser. No. 08/684,131, filed Jul. 19, 1996 now U.S. Pat. No. 5,730,115, granted Mar. 24, 1998 in the name of Richard W. Henderson;
Ser. No. 08/684,132, filed Jul. 19, 1996 now U.S. Pat. No. 5,772,425, granted Jun. 30, 1998 in the name of Richard W. Henderson;
Ser. No. 08/829,037, filed Mar. 31, 1997 now U.S. Pat. No. 5,899,682, granted May 4, 1999 in the names of Richard W. Henderson and Kerryl L. Henderson; and
Ser. No. 08/916,764, filed Aug. 19, 1997 now U.S. Pat. No. 5,551,865, granted Oct. 19, 1999 in the names of Richard W. Henderson and E. Randolph Lucas.